The goal of the surgical treatment of atrial fibrillation is to block or interfere with impulses radiating from ectopic foci inside the pulmonary veins that triggered atrial fibrillation. Among the first intra-heart surgical treatments for atrial fibrillation was demonstrated by the Leipzig group in a procedure referred to as, endocardial linear lesion, to connect the pulmonary vein to the mitral annulus during open heart surgery.
The Mayo Clinic is known for another open heart surgical procedure, termed the Maze procedure, in which multiple cuts are created in the atrial muscle in a maze pattern. These cuts produce scar tissue which does not carry electrical impulses and as a result the stray impulses causing atrial fibrillation are eliminated producing a normal coordinated heartbeat.
More recently, cardiology specialists called, electrophysiologists, have used cardiac catheters to ablate the heart tissue without the need for open heart surgery. In this procedure, an RF catheter is inserted into the atrium and a series of ablations or burns are performed around the mouth of the pulmonary vein and the left atrial wall. The ablations also form scar tissue blocking stray electrical impulses to restore normal heartbeat. During RF catheter ablation, lesion depth, extension and volume are related to the design of the ablation electrode and the RF power delivered.
Among the complications that may arise is pulmonary vein stenosis, if the ablations are too close to the mouth of the pulmonary vein. Another serious and, possibly fatal, complication is atrial-esophageal fistula caused by thermal penetration of the walls of the atrium and esophagus. The atrial-esophageal fistula can lead to pericarditis, or fluid between the outer wall of the heart and the pericardium restricting the heartbeat, hemorrhage, or other life threatening conditions.
The atrial-esophageal fistula or hole in the esophageal wall may result, in part, from simple anatomy and the RF power needed to develop ablations, as well as the design of the catheter electrode tip and other contributing factors, such as movement of the esophagus during the procedure.
The esophagus is located at the center of the posterior mediastinum and is separated from the atrium only by the pericardial sac and/or a thin layer of fatty tissue and may be in contact with the atrium. The left atrium wall thickness is about 2-4 mm and the esophagus thickness is about 2-3 mm. The esophagus is supported at it's upper end near the trachea and transits the diaphragm to connect with the stomach. The esophagus is supported at its lower end by the diaphragm. The thoracic portion of the esophagus between the trachea and the stomach is mobile and loosely restrained only by soft tissue. This allows the esophagus to move in response to swallowing food, cardiac and lung movement, as well as upper body movements. This flexibility of the esophagus complicates the problem of avoiding atrial-esophageal fistula.